Abstract
Thanks to the improvement of surveying equipments, i.e. Terrestrial Laser Scanners (TLS) and Unmanned Aerial Vehicles (UAV), dense point clouds and very precise 3D models of inaccessible rock cliffs can be obtained. Both commercial and self-developed data processing software packages allow the extraction of some parameters regarding discontinuity sets (i.e. orientation, intensity, Vb, etc.). Nevertheless, maps with the distribution of such parameters are still not common. A procedure for obtaining raster maps with the distribution of significant parameters for the geomechanical characterization of rock cliffs, open pit mine slopes and tunnel faces is presented in this paper. Some selected case studies in the Italian Alps will be presented
1. INTRODUCTION
Thanks to the improvement of surveying equipment and data processing software, an increasing use of TLS (Terrestrial Laser Scanning) for investigating and monitoring rock cliffs has been made during the last decade (Figure 1).
Both scanning speed and operational range have been significantly increased, reducing the surveying time and increasing the extension of the study areas.
More recently, professional UAVs (Unmanned Aerial Vehicles) equipped with optical and thermal cameras (Figure 2) as well as laser scanners became available, making it possible to integrate co-registered TLS and UAV data into a unique 3D software environment, reducing shadow areas and providing very detailed 3D models of inaccessible rock cliffs with an accuracy of few centimeters.
By applying proper software packages, it’s now possible to extract not only the attitude of rock mass discontinuity surfaces directly from the point cloud, but also to map the distribution of significant parameters influencing the behavior of the rock mass, e.g. frequency, spacing, P21 (cumulative tracelength per unit area), Vb (elementary rock volume), etc. Moreover, the possibility of draping high-resolution digital images over either a point cloud or a 3D mesh derived from it enhances the resolution of the 3D model and the capability of extracting geometrical information from the surveyed surface.
